Radius attachment for lathes



Nov. 9, 1948.

A. M. BELL, JR

RADIUS ATTACHMENT FOR LATHES 4 Sheets-Sheet 1 Filed Nov. 22, 1946 mmvrm ALLEN M- BELL, .JR-

J MZKMJJYH ATTORNEYS- Nov. 9, 1948. A. M. BELL JR 2,453,111

I RADIUS ATI'TACHMENT FOR LATHES Filed Nov. '22, 1946 4 Sheets-Sheet 2 INVENTOR. ALLEN M- EELL, .JR.

ATTORNEYS- A. M. BELL, JR

RADIUS ATTACHMENT FOR LATHES Nova 9, 1948.

Filed NOV. 22, 1946 4 Sheets-Sheet 3 mm. Emmmmmcml v 5 a 9 7 mm m m 1 2 2 W. a m a M Mm a 7% x F A; 1/. M v I liiiiiiiiiiiii Flam NOV. 9, 1948. BELL, JR 2,453,111

RADIUS ATTACHMENT FOR LATHES Filed Nov. 22, 1946 4 Sheets-Sheet 4 &

A pi? IllllU- F1 lEL mmvron. ALLEN M. BELL, JR-

AT TURNEYS- Patented Nov. 9, 1948 UNITED STATES PATENT, o 'Fic's 2,453,111 Remus ATTACHMENT FOR Lamas Allen M. Bell, Jr., Philadelphia County, Pa. Application November 22, 1946, Serial No. 711,766

. 2 Claims. (Cl.82--11) (Granted under the act of March 3, 1883, as

amended April 30, 1928; 3'70 0.6;. 757) The invention described in the following specification and claimsmay be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to a lathe or an attachment for a lathe which may be easily mounted upon the usual lathe bed and, more particularly, relates to a device for cutting a curved surface having a large radius of curvature on a work piece having a small diameter.

In all the prior devices, with which I am familiar, for cutting a curved surface in the shape of a circular. arc, the cutting tool is pivotally mounted for manual or mechanical turning movement about a pivot mounted on the cross head or compound rest of the lathe. Obviously, in cutting curved surfaces of large radius, the distance must be very large between the tool and the pivot or axis about which it turns and upon which it is suported. This gives rise to a weak support for the cutting tool, which is undesirable.

Accordingly, it is an object of the present invention to provide a lathe or lathe attachment having the following features. The cutting tool is mounted in the customary tool holder supported on the compound of the lathe for straight-line movement lengthwise and crosswise of. the lathe in two mutually perpendicular directions. A stationary pivot is provided which either forms an integral part of or may be adiustably secured in any desired fixed position to a stationary part of the lathe. A link, whose length is equal to the radius which it is desired to cut, is pivotally mounted on this stationary pivot and pivotallyv connected to the tool holder. The tool holder is driven, either mechanically or manually, along one straight line and is free to slide in a perpendicular straight line so that the tool holder and the tool carried thereby move with a translatory movement in a path which is a portion of a circle or arc.

Another object of the present invention is to provide a radius-cutting lathe or lathe attachment, which may be easily substituted for or applied to the ordinary turning lathe, and which is capable of making accurate arcuate cuts, in addition to performing all the functions of the ordinary lathe compound.

A further object. is to provide such a radiuscutting device which is easily adjustable for making arcuate cuts of different radii.

A still further object of this invention is to provide a lathe tool, which will accurately cut a circularly curved surface and which will later iii exactly reproduce or duplicate this curved surface, and which will cut a concave curved surface and a convex curved surface which surfaces exactly interfit and mate together.

Finally, it is an object of the present invention to incorporate all the foregoing advantageous features in a simple, compact and inexpensive lathe or lathe attachment which may be easily operated and which requires no additional space.

These and other objects are attained by the improvements comprising the present invention, which may be stated in general terms as including a lathe bed having sliding ways on it, a tool holder slidable longitudinally and transversely of said ways, a fixed pivot mounted on a stationary part of the lathe, and a link which is the length of the desired radius, which is to be cut, andis otally attached to said tool holder so that the tool holder is constrained to move in a circularly curved path of the desired radius.

For a further exposition of this invention reference may be had to the annexed specification and accompanying drawings.

In the drawings:

Fig. 1 is a perspective view showing the lathe attachment.

Fig. 2 is a view in vertical cross section showing a modified form of radius-limiting link which is adjustable.

Fig. 3 is a top or plan view of the headstock end of the lathe and the adjacent parts.

Fig. 4 is a view in front elevation of the parts at the headstock end of the lathe.

Fig. 5 is a vertical longitudinal cross section on zig-zag line 5--5 of Fig. 3 on an enlarged scale.

Fig. 6 is a vertical transverse cross section on an enlarged scale on line 6-4 of Fig. 4.

Fig. 7 is a vertical transverse cross section on an enlarged scale on line of Fig. 4.

Fig. 8 is a vertical longitudinal cross section on an enlarged scale on line 8-8 of Fig. 3.

Fig. 9 is a top or plan view showing a modification of a portion of the headstock and of the lathe and the adjacent parts.

Fig. 10 is a front elevation of the parts at the headstock end of the lathe as shown in Fig. 9.

Fig. 11 is a transverse vertical cross section on line ll--H of Fig. 9 as viewed in the direction of r Power is applied to the headstock either by means of a self-contained electric motona cone pulley for receiving a bolt, or other convenient conventional device. Rotatably mounted in headstock I2 is a work receiving chuck I3 in which is firmly secured a rod WW (as shown in Figs. 3 and 4) or other work piece W (as shown in Fig. 1) of small diameter, on which a circularly curved surface of long radius is to be turned. Slidably mounted on ways III and H is a carriage which includes compound I4, which is movable longitudinally of the lathe bed in one straight line,

and which is also movable transversely of the tion (not shown) from the lead screw I5. Upon the compound I4 is mounted a cross slide II having groove I8 in it. In groove I3 is secured the tool holder 19 which carries the tool bit 20 having at one end of it a cutting tool 2 I.

Referring to Fig. 1 for a convenient showing,

k anchor clamp 22 engages the under side of the slide ways I9 and II. Through anchor clamp 22 passes anchor clamp bolt 23 which is secured by means of a nut 24 to anchor base 25 whose lower face is suitably shaped to interfit with the slide ways In and II. To the upper surface of anchor base 25 is secured anchor bed 26 having in its upper surface a transversely extending groove 21.

Figs; 5, 7 and 8 show in greater detail the anchor bed 26 having groove 21 in it into which extends a ridge 28 forming part of a clamp bracket 29 in which is screw threadedly engaged a bracket-adjusting screw 30 having a protruding head 3I and a smooth portion 32 intermediate two collars. Bracket-adjusting screw 30 engages with an inverted slot in a part attached to adjustable bracket 33 which is slidable transversely of clamp bracket 29 and longitudinally of the lathe. A pair of bracket securing screws 34 each has at its upper end a nut 35 by means of which the clamp bracket 29 and the adjustable bracket 33 may be firmly secured in a selected position along the groove 21 in the anchor bed 26. At one end adjustable bracket 33 has a hole 36 through it in which is mounted a pivot pin 31 having an enlarged head 38 knurled or otherwise formed to be grasped by the hand so that pin 31 is readily inserted into or removed from hole 36.

A link 39 has in it holes, each adjacent one of its ends, whose centers are spaced apart by a distance exactly equal to the radius which it is desired to cut. Pin 31 passes through one of the holes in link 39 as well as through hole 36 and pivotally secures link 39 to adjustable bracket 33.

Cross slide I1 has a pair of bolts 40 secured to it. Mounted on one of these bolts 40 is a compound clamp M which has a perforation in it through which the bolt 40 passes. The compound clamp has a notch 42 in one face arranged to fit over the corresponding shoulder of the cross slide I'I. Nut 43 on bolt 40 secures the compound clamp M to the cross slide I'I. Compound clamp 4I also has a hole 44 passing through it, in which is located a pivot pin 45 having a knurled or like head 46. Pin 45 a o P 51 3 this invention is as follows.

7 4' through the other hole in link 39 and serves to pivotally secure the link 39 to the cross slide I1 and consequently to the compound I4 and to the tool holder I9.

The operation of the radius cutting device of Assume that it is desired to cut a concave, circularly curved surface in the work piece W shown in Fig. 1. The first step is to select a link having a distance between the centers of the holes therein equal to the radius which is to be out. In readying the lathe for this operation, the cross feed nut (not shown) in the lathe is disengaged and removed if possible. This leaves the compound I4 (and the parts carried thereby) free to slide back and forth transversely of the bed of the lathe. The compound I4 (and consequently the cutting tool 2| carried by it) is fed longitudinally of the lathe,'this feed being either manual or mechanical. The work piece W is then placed in the chuck I3 of the lathe, and the tool bit 29 is placed in the tool holder I9 and secured therein. The anchor clamp 22 is placed beneath the ways In and II. The anchor base 25 is mounted on the ways I0 and II above the anchor clamp 22, and the anchor clamp bolt 23 is passed through suitable holes in the anchor base 25 and the anchor clamp 22. Nut 24 is then mounted on the anchorclamp bolt. Anchor bed 26 is located so as to project towards the operator's side of the lathe, in this case, since it is desired to make a concave out. In case it is desired to make a convex cut, the anchor bed is arranged to project toward the back or far side of the lathe bed away from the operator. The clamp bracket 29 and the adjustable bracket 33 are then secured in position on the anchor bed 25 by means of the bracket securing screws 34 and the cooperating nuts 35. The nut 43 is removed from the compound of the lathe and the compound clamp M is fastened in place by passing the bolt 49 through the hole in the compound clamp 4| so that the notch 42 fits against a shoulder on the cross slide I'I. Tightening nut 43 then secures the compound clamp 4I tightly to the compound I4 and provides a motion-transmitting connection to all the parts carried by the compound I4, including the cutting tool 2|. The selected link 39 is then placed so that the holes in it are aligned with the holes in the adjustable bracket 33 and in the compound clamp 4I'. Pin 31 is slipped through the holes in the adjustable clamp 33 and one hole in the link 39. Pin 45 is slipped through the holes in the compound clamp H and the other hole in link 39. Link 39 is thus pivotally secured between the adjustable bracket 33 and the compound clamp H. In case it is desired to cut a curved surface tangent to a surface of work piece W, the anchor assembly is now slid along ways I0 and II of the lathe until link 39 is parallel with the axis of the anchor assembly which extends transversely or crosswise of the lathe. This insures that the axis of the pivot pin 31 is located in the proper position. Nut 24 and nuts 35 are then tightened to secure the anchor assembly, the clamp bracket 29, and the adjustable bracket 33 firmly in their proper positions. Before the nuts 35 are tightened, the adjustable bracket 33 may pound I4 is moved longitudinally of the lathe and consequently longitudinally of the work piece W until the cutting tool 2| is opposite that portion of the work piece W where it is desired to begin the cut. The cutting tool 2| is then fed towards the turning axis of the lathe to the desired depth of the first cut. Power is then applied to the lathe to start the rotation of the workpiece W. The compound 14 and consequently all the parts carried by it, including the cutting bit 2|, are fed longitudinally of the lathe, either manually or mechanically. Since the compound is free to slide transversely of the lathe but is held about the center of pin 31 as a pivot,

cutting tool 2| moves with a translatory movement'along a pathwhich is a portion of the circumference of a circle whose radius is the are turned back to the starting point. The. cutting tool 2| is fed in towards the turning center of the lathe a, distance equal to the desired depth of the second cut and the whole process repeated- 9 receive one end 50 of a second link rod 53. End 50 7 distance between the centers of the pins 31 and again and again in a series of cuts until sufilcient metal has been removed from the work piece W to leave a curved surface of the desired radius. In case the set-up has been made so that the cutting tool 2| (and consequently the curved surface cut) is tangential to the surface of the work piece W, the final cut will terminate at this point of tangency.

Fig. 3 shows particularly that this device operates most efficiently whenthe feed is substantially at right angles to the long axis of the link 39. When the direction of the'feed and the axis of the link 39 coincide, the device has a dead center and will not operate at all. As a practical matter, the device operates best when the angle between the'direction of feed and the axis of the link 39 is greater than ten degrees. This efficiency progressively increases as the angle increases, being greatest, as has been stated, at

ninety degrees. 'It will thus be seen that it is not practical to cut a complete hemisphere with this device, although it can be doneby the use of the device andby employing a hand feed when the angle between the axis of link 39 and the direction of feed is too small to effectively control the turning movement of cutting tool 2| about the axis of pin 31 as acenter.

For turning a concave surface similar to a dish or bowl, especially if it is to be turned in the end of a work piece or that surface which extends transversely of the bed of the lathe, the

compound l4 and thecutting tool 2| carried thereby may be fed transversely of the lathe, either manually or mechanically, while at the same time, the longitudinal feed of the compound is disengaged so that the compound I4 is free to slide parallel to the ways Ill and H.

Fig. 2 shows a modification of the device in which the link 39 is adjustable. 39 is variable in length, adjustable bracket 33 has mounted in it a perforated link head 4'! through which the pin 31 extends. At its outer end link head 41 carries a link rod 48 having a right hand thread on it. A plurality of link rods 48 of varying lengths are employed so that one approximately of the desired length may be selected. The opposite end of link rod 48 has screw threaded engagement with a turnbuckle 49. Tumbuckle 49 also has in it a cavity adapted to When the link has screw threads of the opposite pitch from those on the adjacent end of rod 48, in this case lefthand threads. The other end 5| of the second rod 53 has screw threads the same as those on rod 48, in this case right-hand. The rod 53 having the ends 59-5! may be short in length, for example, two inches. This rod fits into a perforated link head 52 adapted to be secured in the compound clamp 4| by pin 45 .which passes through alignedholes in the compound clamp 4| and in the link head 52. The ends oi: turnbuckle 49 en age locknuts 54. The construction of Fig. 2 therefore provides a link which is readily adjustable to a wide variety of lengths.

Figs. 9, 10 and 1-1 show a second modification of the device, this modification being adapted to out small radii. In this modification theadjustable bracket 55 is somewhat different in shape than the adjustable bracket 33 but it performs the same function. Adjustable bracket 55 has a hole at its end away from the headstock l2 in which hole is pivotally mounted apinzportion 59 ofan eccentric, indicatedge'nerally at-"51. Eccentric 51 has a crank or displaced portion '53 and a second pin portion 59. The compound clamp has a portion 60 which has the same function and corresponds to the compound clamp 4| although it is of slightly different shape. Compound clamp 60 has a hole in it in which the pin portion 59 of the eccentric is rotatably received. The axes of the pin portions 56 and 59 are ofl'set by means of the crank or displaced portion 58 by an amount which is equal to the radius which is to be cut.

- Pin portion 60 has at its end a bolt portion 5| which is screw-threaded to receive a 'nut 62 on it.. Likewise, pin portion 59 has a bolt portion 63 on it which is also screw-threaded to receive a nut 6-i.- The adjustable bracket 55 and the compound clamp 69 are offset vertically so that they do not strike or contact one another but are free to ride over one another. This permits the distance between the axes of the pin portions 55 and 59 to be made as small as may be desired.

Summary From the foregoing it will be seen that this invention provides a lathe or latheattachment in which the cutting tool is mounted so as to be driven either manually or mechanically along one straight line while it is free to slide along a straight line at right-angles to the first, there being provided, on a stationary part of the lathe,

a pivot to which the cutting tool support is pivotally secured so that the cutting tool is constrained to move along a curvedpath whose radius is equal to the distance between the axes of the two pivots.

I claim:

1. In a lathe having the conventional bed provided with elongated ways and the conventional headstock adapted to receive and rotate the workpiece to be turned and the conventional toolholding post movable manually or mechanically both transversely and longitudinally of said lathe bed, an attachment for cutting a curved surface having a large radius on a workpiece having a small diameter, including, an anchor base having a surface arranged to interfit with the ways of the lathe, an anchor clamp havin a surface arranged to fit beneath the ways of the lathe, an anchor clamp bolt arranged for connection with said anchor base and said anchor clamp and adapted to secure said anchor base in a selected fixed position, an anchor bed having a perforation in it and firmly but detachably secured to said anchor base and having an elongated groove therein extending transversely of the bed of the lathe, a clamp bracket having a ridge extending from a surface thereof into the groove in said anchor bed, a bracket securing screw having engagement with said anchor bed and with said.

clamp bracket so as to secure said clamp bracket in a selected fixed position along said anchor bed, a compound clamp having two perforations in it and a slot in one face thereof so that said compound clamp is adapted to engage with the tool holder of the lathe and to be secured to said tool holder by means of a bolt passing through one of the perforations in said compound clamp, a link having a pair of perforations in it, and a pair of pins passing through the perforations in said link and seeming said link to said clamp bracket and to said compound clamp so that said compound clamp turns at the end of said link about the pin in said clamp bracket as a center and thereby moves the tool holder of the lathe l. a in an arc whdse radius is the distance between the centers of the pins. 7

2. The structure of claim 1 wherein the link consists of a pair of rods axially aligned and having threaded ends opposing each other and a turnbuckle threadably engaging the threaded I ends of said rods so as to secure them together to make said links length adjustable to the size of The following references are of record in the file of this patent: v

UNITED STATES PATENTS Number Name Date 1,448,848 Lafler Mar. 20, 1923 2,053,470 Flodin Sept. 8, 1936 OTHER REFERENCES Popular Science, February, 1945, page 191. 

